Merle Dargus of Red Wing wrote to Whistleblower about his daughter's experience buying a ticket online. She thought she was paying $250 but by the time she entered her info and hit the "purchase" button, the price had leaped to $450. "She spoke with 5 managers on the phone at [the airline] and they all claim fares can change at any moment," Dargus wrote. Travel consumer advocate Christopher Elliott said this happens all the time. There can be dozens of fares available for each flight and a computerized registration system is constantly adjusting airlines' offerings, he said. The problem lies with web caching, according to Elliott. "In order to improve the performance of the website people are booking from, the airlines and online agencies are doing something called caching, which basically means they are storing a copy [of the screen] on their local website." "When you are querying the airline website you're not actually getting a real-time fare, you're accessing a cache. So when you go back and say you want to book it, you may have one or two other people somewhere else asking to book that same fare. So as a result the computer goes, oops that fare is not available anymore and it goes to the next fare," Elliott said. The airlines could fix the problem and provide real-time fares, according to Elliott. "They're just too cheap to do it." Elliott said that if Dargus' daughter would have taken a screen grab of the final web page just before she hit the "purchase" button, she could have used that image to contest any increase in price. Instructions on how to take a screen grab (picture) are available online.